Multi-zone EC windows

ABSTRACT

Thin-film devices, for example, multi-zone electrochromic windows, and methods of manufacturing are described. In certain cases, a multi-zone electrochromic window comprises a monolithic EC device on a transparent substrate and two or more tinting zones, wherein the tinting zones are configured for independent operation.

INCORPORATION BY REFERENCE

An Application Data Sheet is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority to as identified in the concurrently filed Application Data Sheet is incorporated by reference herein in its entirety and for all purposes.

FIELD

Embodiments disclosed herein relate generally to optical devices, and more particularly to methods of fabricating optical devices and particularly to electrochromic (EC) windows having multiple tinting zones.

BACKGROUND

Electrochromism is a phenomenon in which a material exhibits a reversible electrochemically-mediated change in an optical property when placed in a different electronic state, typically by being subjected to a voltage change. The optical property is typically one or more of tint, transmittance, absorbance, and reflectance. For example, one well known electrochromic material is tungsten oxide (WO₃). Tungsten oxide is a cathodically tinting electrochromic material in which a tinting transition, bleached (untinted) to blue, occurs by electrochemical reduction. When electrochemical oxidation takes place, tungsten oxide transitions from blue to a bleached state.

Electrochromic materials may be incorporated into, for example, windows for home, commercial and other uses. The tint, transmittance, absorbance, and/or reflectance of such windows may be changed by inducing a change in the electrochromic material, that is, electrochromic windows are windows that can be darkened and lightened reversibly via application of an electric charge. A small voltage applied to an electrochromic device of the window will cause it to darken; reversing the voltage causes it to lighten. This capability allows control of the amount of light that passes through the windows, and presents an opportunity for electrochromic windows to be used as energy-saving devices.

While electrochromism was discovered in the 1960s, electrochromic devices, and particularly electrochromic windows, still unfortunately suffer various problems and have not begun to realize their full commercial potential despite much recent advancement in electrochromic technology, apparatus, and related methods of making and/or using electrochromic devices.

SUMMARY

Thin-film devices, for example, electrochromic devices for windows, and methods of manufacturing are described. Embodiments include electrochromic window lites having two or more tinting (or coloration) zones, where there is only a single monolithic electrochromic device on the lite. The tinting zones are defined by virtue of the means for applying potential to the device and/or by a resistive zone between adjacent tinting zones. For example, sets of bus bars are configured to apply potential across separate zones (areas) of the device and thereby tint them selectively. The advantages include no visible scribe lines in the viewable area of the EC window due to cutting through the EC device to make separate devices that serve as tinting zones.

One embodiment is an electrochromic window lite including a monolithic EC device on a transparent substrate, the monolithic EC device including two or more tinting zones, each of said two or more tinting zones configured for operation independent of the others and each having its own associated bus bars, where the two or more tinting zones are not separated from each other by isolation scribes. That is, the EC device stack is not cut through, but rather is intact as a monolithic device. For example, there may be two tinting zones on the lite and the associated bus bars arranged are located at opposing edges of the lite (e.g., vertically oriented), wherein a set of bus bars is associated with each of the two tinting zones.

Bus bars may be configured to enhance coloring of tinting zones. In certain embodiments, bus bars have varying width along their length; the varying width of the bus bars may enhance the tinting front and/or promote selective tinting in a particular tinting zone via voltage gradients. In other embodiments, bus bars may be composites, having both high electrically conductive regions and resistive regions, configured to enhance tinting fronts and/or promote selective tinting in a particular tinting zone via voltage gradients. One embodiment is directed to an electrochromic window lite comprising a monolithic EC device on a transparent substrate and at least one pair of lengthwise variable bus bars configured to produce a tint gradient zone on the monolithic EC device when energized.

In certain embodiments, the two or more tinting zones are separated by a resistive zone which inhibits, at least partially, the flow of electrons, ions or both across the resistive zone. Resistive zones may, e.g., be parallel to bus bars and/or orthogonal to bus bars. Resistive zones may include modification of the EC device and/or one or both transparent conductor layers (TCOs) of the EC device. Monolithic EC lites having two or more tinting zones may be integrated into insulating glass units (IGUs). The mate lite may or may not also be an electrochromic lite, and may or may not also have tinting zones.

One embodiment is directed to an electrochromic window lite comprising a monolithic EC device disposed on a transparent substrate and a resistive zone. The monolithic EC device is comprised of first and second transparent conductor layers and an EC stack between the first and second transparent conductor layers. The resistive zone in one of the first and second transparent conducting layers. The resistive zone has a higher electrical resistance than a portion of the one of the first and second transparent conducting layers outside the resistive zone. In one case, the resistive zone is a linear region in the one of the first and second transparent conducting layer with thinner or absent material.

Certain aspects of the disclosure pertain to an electrochromic window lite that may be characterized by the following features: a monolithic EC device on a transparent substrate, the monolithic EC device comprising: two or more tinting zones, each of the two or more tinting zones configured for operation independent of the others and having its own associated bus bars. In certain embodiments, the two or more tinting zones contain only a partial cut through the uppermost TCO of the monolithic EC device to form a resistive zone between each of said two or more tinting zones.

In certain embodiments, the associated bus bars located at opposing edges for each of the two tinting zones. In certain embodiments, the electrochromic window lite is incorporated into an insulated glass unit, which may have a mate lite that is (i) not an electrochromic lite or (ii) a monolithic electrochromic lite with a single tinting zone, or (iii) a monolithic electrochromic lite with two or more tinting zones (where the tinting zones of the mate lite may be aligned with those of the electrochromic window lite), or (iv) an electrochromic lite with three or more tinting zones. In such embodiments, the electrochromic window lite may be configured to tint in one or more tinting zones to <1% T.

In some implementations, the resistive zone substantially spans across the monolithic EC device. In some implementations, the resistive zone is between about 1 nm wide and about 10 nm wide. In certain embodiments, the resistive zone is formed by removing between about 10% and about 90% of the uppermost TCO material along the resistive zone. As an example, the resistive zone may be formed by laser irradiation of the uppermost TCO. As a further example, each of the two or more tinting zones associated bus bars are formed by laser irradiation during formation of the resistive zone by cutting through a single bus bar.

Other aspects of the disclosure pertain to methods of forming a monolithic EC device comprising two tinting zones, where the methods may be characterized by the following operations: (a) forming the monolithic EC device; (b) applying a single bus bar to the top

TCO of the monolithic EC device; (c) cutting through the single bus bar along its width; and, (d) cutting at least part way through the top TCO, but not through the electrode layer adjacent to the top TCO, to form a resistive zone between the two tinting zones. In certain embodiments, operation (c) forms separate bus bars for each of the two tinting zones from the single bus bar. In some implementations, operations (c) and (d) are performed in a single cutting step.

In some implementations, the resistive zone substantially spans the width of the monolithic EC device. In certain embodiments, the resistive zone is between about 1 nm wide and about 10 nm wide. In certain embodiments, the resistive zone is formed by removing between about 10% and about 90% of the uppermost TCO material along the resistive zone. As an example, the resistive zone may be formed by laser irradiation of the uppermost TCO.

Another aspect of the disclosure concerns electrochromic window lites characterized by the following features: an EC device on a transparent substrate, the EC device comprising bus bars; a region of the transparent substrate that is not covered by the EC device, where the region capable of providing, when not mitigated, a bright spot or bright region when the EC device is tinted; and an obscuring material over the region, wherein the material has a lower transmittance than the substrate. In some embodiments, the region is a pinhole, a scribe line, or an edge line.

Yet another aspect of the disclosure concerns methods of obscuring a potentially bright area produced by a region of a transparent substrate that is not covered by an EC device. Such methods may be characterized by the following operations: (a) providing an electrochromic lite having the EC device on a substrate; (b) identifying a site of the potentially bright area on the substrate; and (c) applying an obscuring material to the site. The obscuring material has a lower transmittance than the substrate. In certain embodiments, the region is a pinhole, a scribe line, or an edge line.

These and other features and advantages will be described in further detail below, with reference to the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description can be more fully understood when considered in conjunction with the drawings in which:

FIG. 1 depicts fabrication of an IGU with an EC lite and associated tinting schemes.

FIGS. 2A and 2B depict an IGU having an EC lite with two tinting zones delineated by laser scribe, and associated tinting schemes, respectively.

FIGS. 3A and 3B depict fabrication of an IGU with an EC lite having tinting zones configured on a monolithic EC device and associated tinting schemes, respectively.

FIG. 3C depicts various tinting schemes as a function of tinting front of tinting zones.

FIGS. 3D and 3E depict fabrication of an IGU having two EC lites, where each of the EC lites has two tinting zones, and associated tinting schemes, respectively.

FIGS. 4A-C depict fabrication of an IGU with an EC lite and associated tinting schemes, respectively.

FIGS. 4D-F depict EC lites, each having a gradient tinting zone.

FIGS. 5A and 5B depict fabrication of an IGU with an EC lite and associated tinting schemes, respectively.

FIG. 5C depicts a perspective and a cross section of an EC device having two tinting zones separated by a resistive zone.

FIG. 5D depicts a perspective and a cross section of an EC device having two tinting zones by virtue of a resistive zone.

FIG. 5E shows graphs of V_(TCL) for two transparent conducting oxide layers of an EC device configured with a resistive zone created by inhibiting the electrical conductivity of only one of the transparent conducting oxide layers.

FIG. 5F depicts a tinting pattern of the EC lite described in relation to FIG. 5C.

FIGS. 5G to 5K depict EC devices configured with a resistive zone created by inhibiting the electrical conductivity of only one of the transparent conducting oxides.

FIG. 6A depicts a resistive zone establishing a closed perimeter defining a separate tinting zone.

FIG. 6B depicts a resistive zone establishing an open perimeter defining a separate tinting zone.

DETAILED DESCRIPTION

Certain embodiments are directed to optical devices, that is, thin-film devices having at least one transparent conductor layer. In the simplest form, an optical device includes a substrate and one or more material layers sandwiched between two conductor layers, one of which is transparent. In one embodiment, an optical device includes a transparent substrate and two transparent conductor layers. Certain embodiments described herein, although not limited as such, work particularly well with solid state and inorganic electrochromic devices.

FIG. 1 depicts fabrication of an IGU, 120, with an EC lite, 100, which includes a monolithic EC device and associated pair of bus bars, 105, which energize the device each via a transparent conductor, the pair of transparent conductors sandwich the EC materials between them so that a potential can be applied across the device materials. The IGU is fabricated by combining EC lite 100 with a spacer, 110, and a mate lite, 115, along with the appropriate sealants and wiring (not shown) to the bus bars. As depicted on the bottom half of FIG. 1, the IGU can be transparent (left), tinted to an intermediate state (middle) or fully tinted (right). However, there is no possibility of tinting the viewable area of the lite in different areas or “zones.” Conventional technology does exist to achieve this end, however.

FIG. 2A depicts an IGU, 220, having an EC lite, 200, with two tinting zones delineated by laser scribe, 225. Each tinting zone has an associated pair of bus bars, 205 and 207, respectively. The EC lite 200 may be incorporated into an IGU, 220, as described in relation to FIG. 1. Scribe line 225 cuts through both of the transparent conductor layers which sandwich the electrochromic materials, along with the EC device layer(s), so that there effectively two EC devices, one corresponding to each tinting zone, on the EC lite 200. Scribe line 225 may not be visually discernible when the EC lite is not tinted, as depicted in FIG. 2A, i.e. in the untinted state (bleached or neutral state).

FIG. 2B depicts three possible tinting schemes of IGU 220. As shown, IGU 220 may have the top zone tinted and the bottom zone untinted (left), the top zone untinted and the bottom zone tinted (middle) or both the top and bottom zones tinted (right). Although such windows offer flexibility in tinting, when both zones are tinted, scribe line 225 is visually discernible and is unattractive to an end user because there is a bright line across the middle of the viewable area of the window. This is because the EC material in the area has been destroyed and/or deactivated from the scribe line that cut through the device. The bright line can be quite distracting; either when one is looking at the window itself, or as in most cases, when the end user is trying to view things through the window. The bright line against a tinted background catches one's eye immediately. Many approaches have been taken to create tinting zones in optical devices, but they all involve some sort of physical segmentation of a monolithic optical device into two or more individually operable devices. That is, the functionality of the EC device is destroyed along the scribe line, thus effectively creating two devices from a monolithic single device. Certain embodiments described herein avoid destroying the EC device function between adjacent tinting zones.

One approach to overcoming the visually distracting bright line created by a laser scribe in the viewable area of an EC lite is to apply a tinted material to the lite, e.g. on the scribe line or on an opposing side of the lite, in order to obscure or minimize the light passing through the scribe area. Thus, when tinting zones adjoining the scribe are tinted, the scribe line will be less discernible to the end user. When neither of the adjoining tinting zones is tinted, the tinted material in the scribe line area will be almost or completely indiscernible because it is a thin tinted line against a large untinted background, which is harder to see than a bright line against a tinted background. The thin tinted line need not be opaque, a limited amount of absorption of the visible spectrum can be used, e.g., absorption that will tone down the bright line created when the full spectrum emanates through scribe line 225. Methods for obscuring pinhole defects in optical devices are described in, for example, described in U.S. Provisional Patent Application Ser. No. 61/610,241, filed Mar. 13, 2012, and described in PCT Application Serial No. PCT/US2013/031098 filed on Mar. 13, 2013, which are both hereby incorporated by reference in their entirety. Whether obscuring pin holes, scribe lines, edge lines, or the like, the methods obscure bright areas on EC devices, e.g. by applying tinted material to such areas to make them harder to see to the end user. Edge lines exist where a coating such as a monolithic electrochromic coating, does not extend to the spacer of an IGU (e.g., element 110 of FIG. 2A). In this region, a bright line or wider area is visible when viewing the IGU directly. As understood by those of skill in the art, the obscuring methods described in the present application and in PCT/US2013/031098 have equal applicability to pin holes, edge lines, scribe lines, and the like. The methods described in the aforementioned patent application are particularly useful for obscuring scribe or edge lines in the visible area of an optical device such as an EC device. One embodiment is a method of obscuring a scribe line in the viewable area of an EC window, the method including applying a method used to obscure pinholes as described in the aforementioned U.S./PCT Patent application. For example, one method includes applying a tinted material to the scribe line and optionally the area adjacent the scribe line. In another example, the glass at the bottom of the scribe line trench (and optionally some adjoining area) is altered so as to diffuse light that passes therethrough, thus ameliorating the “bright line” effect.

Tinting Zones

As discussed above, certain embodiments described herein avoid destroying the EC device functionality between adjacent tinting zones. Though scribe lines may be visually obscured by application of tinted materials to the lite as described above, the inventors have found that it may be often preferable to maintain the functional integrity of a monolithic EC device, rather than scribe it into discrete devices and thus conventional tinting zones. The inventors have discovered that tinting zones may be created by: 1) configuring the powering mechanism (e.g. bus bars, wiring thereto and associated powering algorithms) of the optical device appropriately, 2) configuring the EC device such that adjacent tinting zones are separated by a resistive zone, or 3) combination of 1) and 2). For example, number 1) may be achieved by appropriately configuring one or more bus bars such that they can be activated independently of other bus bars on the same monolithic EC device. Thus tinting zones are created without the need to physically separate individual EC devices to create corresponding tinting zones. In another example, a resistive zone allows coloration and bleaching of adjacent tinting zones on a single EC device without destroying functionality in the resistive zone itself. A resistive zone can refer to an area of the monolithic optical device, e.g. an EC device, where the function is impaired but not destroyed. Typically, the functionality in the resistive zone is merely slowed relative to the rest of the device. Impairment might also include diminished capacity for ions in one or more of the layers of the EC device. For example, one or more EC device layers may be made denser and therefore be able to hold fewer ions, and therefore color less intensely than the bulk device, but still function. A resistive zone is achieved in at least one of the following ways: i) the electrical resistivity of one or both of the transparent conductor layers is impaired, ii) one or both of the transparent conductor layers is cut, without cutting through the optical device stack therebetween, iii) the function of the optical device stack (not including the transparent conductor layers) is impaired, and iv) combinations of i)-iv). For example, a resistive zone may be created where one or both of the transparent conductor layers is fabricated thinner or absent, e.g. along a linear region, so as to increase electrical resistivity along the linear region of the resistive zone. In another example, one of the transparent conductor layers may be cut along the width of the device, while the other transparent conductor is left intact, either of uniform thickness or thinner, along the resistive zone. In yet another example, the function of the EC device may be inhibited along a line, so that it resists ion transport, while the transparent conductor layers may or may not be altered along the same line. Resistive zones are described in more detail below in terms of specific, but non-limiting examples. If the resistive zone is in one of the transparent layers, the other transparent layer may be left intact (e.g., uniform composition and thickness).

Configuring Powering Mechanism of EC Devices

One embodiment is an electrochromic window lite including a monolithic EC device on a transparent substrate, the monolithic EC device including two or more tinting zones, each of the two or more tinting zones configured for operation independent of the others and having its own associated bus bar or bus bars. In certain embodiments, the two or more tinting zones are not separated from each other by isolation scribes; that is, the EC device and associated transparent conductors do not have isolation scribes that cut through any of these layers. For example, there may be two tinting zones on the EC lite and two pairs of bus bars, wherein each pair is associated with a tinting zone and both pairs are located at or near opposing edges of the EC lite e.g., the bus bars may be vertically oriented at or near opposing vertical edges with a set of bus bars for each of the two tinting zones. Such lites may be integrated into insulating glass units (IGUs).

FIG. 3A depicts fabrication of an IGU, 300, with an EC lite, 305 having two tinting zones (upper and lower tinting zones) configured on a monolithic EC device, i.e., there are no laser scribes or other physical sectioning (e.g. bifurcation) of the monolithic EC device or transparent conductor layers on the lite. Each of bus bar pairs, 205 and 207, is configured to energize independently of each other. Thus, referring to FIG. 3B, IGU 300 has three tinting schemes besides the untinted state (bleached or neutral state) depicted in FIG. 3A. FIG. 3B shows these three tinting schemes where the top zone may be tinted while the bottom zone is not (left), the bottom zone may be tinted while the top zone is not (middle), or both zones may be tinted (right). In contrast to an EC lite having two distinct EC devices divided at a scribe line, each tinting zone of lite 305, when tinted, has a “tinting front” 310. A tinting front can refer to an area of the EC device where the potential applied across the devices TCOs by the bus bars reaches a level that is insufficient to tint the device (e.g. by movement of ions through the layers of the device to balance charge). Thus, in the example depicted, the tinting front 310 corresponds roughly to where the charge is bleeding off into the area of the transparent conductor that is between the pair of bus bars that are not energized.

The shape of a tinting front may depend upon the charging characteristics of the transparent conductors, the configuration of the bus bars, wiring and powering thereto, and the like. The tinting front may be linear, curved (convex, concave, etc.), zigzag, irregular, etc. For example, FIG. 3B depicts the tinting front 310 as a linear phenomenon; that is, the tinting front 310 is depicted as located along a straight line. As another example, FIG. 3C depicts various tinting schemes as a function of tinting front of each of the tinting zones, in this case lower and upper tinting zones. In the illustrated example, the tinting front is curved (e.g., concave or convex) along the tinting front. In certain embodiments, it may be desirable that when both tinting zones are tinted, the tinting of the EC lite is total and uniform. Thus a convex tinting front may be desirable, so a complimentary concave tinting front may be used in an adjacent zone, or another convex tinting front may be used to ensure sufficient charge reaches the entire device for uniform tinting. In certain cases, the tinting front may not be a clean line as depicted in FIGS. 3B and 3C, but rather have a diffuse appearance along the tinting front due to the charge bleeding off into the adjacent tinting zone which is not powered at the time.

In certain embodiments, when the EC lite with tinting zones is incorporated into an IGU or a laminate for example, the mate lite may also be an EC lite, having tinting zones or not. Insulated glass unit constructions having two or more (monolithic) EC lites are described in U.S. Pat. No. 8,270,059, which is hereby incorporated by reference in its entirety. Having two EC lites in a single IGU has advantages including the ability to make a near opaque window (e.g. privacy glass), where the percent transmission (% T) of the IGU is <1%. Also, if the EC lites are two-state (tinted or bleached) there may be certain tinting combinations made possible, e.g. a four-tint-state window. If the EC lites are capable of intermediate states, the tinting possibilities may be virtually endless. One embodiment is an IGU having a first EC lite having two or more tinting zones and a mate lite that is a monolithic EC lite. In another embodiment, the mate lite also has two or more tinting zones. In this latter embodiment, the tinting zones may or may not be the same in number or aligned with the tinting zones of the first EC lite with which it is registered in the IGU. Exemplary constructs illustrating these descriptions follow.

FIG. 3D depicts fabrication of an IGU, 325, having two EC lites, 305 and 320, where each of the EC lites has two tinting zones, each of the tinting zones created by appropriately configured bus bar pairs, 205 and 207 at or near two opposing edges. In this illustrated example, the tinting zones of EC lites 305 and 320 are registered, that is, they are aligned with each other and of the same area, but this need not be the configuration. For example, the tinting fronts from opposing EC lites 305 and 320 could overlap each other when tinted in another embodiment. FIG. 3D depicts IGU 325 in an untinted state (bleached or neutral state). Also, each of the tinting zones is capable of only two states, tinted or bleached. Even so, this enables a wide range of tinting schemes for IGU 325. Besides the untinted state, IGU 325 is capable of eight tint states. FIG. 3B depicts three of the possible tint states (i.e. where one EC lite of IGU 325 is tinted in one of the three configurations shown in FIG. 3B). FIG. 3E depicts the other five possible tint states for IGU 325. If the top tinting zones of both EC lites are tinted simultaneously, and the bottom two zones are not, then the top half of the IGU is very dark, while the bottom is untinted (top left IGU). If both of the top tinting zones are not tinted, and the bottom two zones are tinted, then the bottom half of the IGU is very dark, while the top is untinted (top middle IGU). If all four zones of the EC lites are tinted, then the entire window is very dark (top right IGU). For example, the combined tinting of all tinting zones in two registered EC lites can achieve <1% T. If one of the top zones in the EC lites is tinted and both of the bottom zones are tinted, then the tint state on the bottom left of FIG. 3E is created. Likewise, if one of the bottom zones is tinted and both of the top zones are tinted, then the tint state on the bottom right of FIG. 3E is created.

One embodiment is an IGU having two or more EC lites, wherein at least two of the two or more EC lites includes multiple tinting zones as described herein. One embodiment is an IGU having two or more EC lites, wherein a first of the two or more EC lites includes multiple tinting zones created by conventional isolation scribes, and a second of the two or more EC lites includes tinting zones as described herein by techniques other than isolation scribes.

Configurations such as those depicted in FIGS. 3B and 3E may be particularly useful in applications such as creating day lighting zones vs. occupant (glare) control zones. Day lighting transoms are very common. For example, creating “virtual transoms” with a piece of glass and thus removing the frame and associated glazier labor has a cost benefit as well as better sight lines. Also, having a variety of tint states such as those depicted in FIGS. 3B and 3E allows for customization of room lighting based on the amount and location of the sun striking individual windows.

Certain embodiments pertain to methods of transitioning an EC lite having two or more tinting zones. In one embodiment, an EC lite having three or more tinting zones is transitioned across the three or more tinted zones from a first zone at one edge of the device, to a second adjacent tinting zone, and then to a third tinting zone, adjacent to the second zone. In other words, the tinting zones are used to give the effect of drawing a physical shade across the window, without actually having a physical shade, since EC windows may eliminate the need for physical shades. Such methods may be implemented with conventional zoned EC lites or those described herein. This is illustrated in FIGS. 4A-C with respect to an EC lite of an embodiment.

Referring to FIG. 4A, an EC lite, 400, is configured with a first set of bus bars, 405, a second set of bus bars 407, and a third set of bus bars, 409. The three sets of bus bars are configured so as to create three tinting zones, respectively. Although EC lite 400 in FIG. 4A is incorporated into an IGU, 420, using a spacer 410 and a mate lite 415, lamination to a mate lite (EC lite or otherwise) or use as a single EC lite is also possible.

Referring to FIG. 4B, assuming that each of the tinting zones is tinted as a two-state zone, then the three tinting zones may be activated sequentially, e.g. from top to bottom as depicted, to create a curtain effect, i.e. as if one were lowering a roller shade or drawing a Roman shade over the window. For example, the top zone may be fully tinted, then the second zone may be fully tinted, finally the third zone may be fully tinted. The tinting zones could be sequentially tinted from the bottom up or in the middle and then the upper and lower zones tinted, depending upon the desired effect.

Another method is to tint the tinting zones as described with respect to FIG. 4B, except that before transition in a particular tinting zone is complete, transition in an adjacent tinting zone begins, which can also create a curtaining effect. In the illustrated example of FIG. 4C, the top tinting zone's tinting is initiated (top left), but before tinting is complete in the top zone, the middle zone's tinting is initiated. Once the top zone's tinting is complete, the middle zone's tinting is not yet complete (top center). At some point during the transition of the middle zone, the bottom zone's tinting is initiated. Once the middle zone's tinting is complete, the bottom zone's tinting is not yet complete (top right), thus the top and middle zones are fully tinted and the bottom zone's tinting is yet to be completed. Finally, the bottom zone is fully tinted. Using tinting zones with intermediate state capability will increase the possible variations of tinting schemes.

Lengthwise Variable Busbars

In certain embodiments, an EC lite may be configured to have one or more tint gradient zones. In these embodiments, the EC lite has an EC device, such as, e.g., a monolithic EC device on a transparent substrate, and also has at least one pair of bus bars with geometry and/or material composition that varies along their lengths to vary electrical resistance lengthwise (lengthwise variable busbars). This variation in resistance can produce a lengthwise gradient in the voltage applied to the EC device supplied across bus bars (V_(app)) and a lengthwise gradient in the local effective voltage (V_(eff)) in the EC device. The term V_(eff) refers to the potential between the positive and negative transparent conducting layers at any particular location on the EC device. The lengthwise gradient of the V_(eff) may generate a corresponding tint gradient zone that varies lengthwise in a region between the pair of bus bars when energized. In these embodiments, the lengthwise variable bus bars will have resistance profiles along their lengths that are functions of both the local bus bar geometry and resistivity. In certain embodiments, the bus bars are designed so that the resistance is lowest at one end of the bus bar and highest at the other end of the bus bar. Other designs are possible, such as designs where the resistance is lowest in the middle of a bus bar and highest at the ends of the bus bar. A description of voltage profiles in various EC devices powered by bus bars can be found in U.S. patent application Ser. No. 13/682,618, titled “DRIVING THIN FILM SWITCHABLE OPTICAL DEVICES,” filed on Nov. 20, 2013, which is hereby incorporated by reference in its entirety.

The local material composition of a bus bar may determine its local resistivity. It is contemplated that the bus bar material composition, and therefore the bus bar resistivity may vary along the length of the bus bar in certain embodiments. The resistivity can be tailored based on various compositional adjustments known to those of skill in the art. For example, resistivity can be adjusted by adjusting the concentration of a conductive material in the bus bar composition. In some embodiments, bus bars are made from a conductive ink such as a silver ink. By varying the concentration of silver in the ink along the length of the bus bar, one can produce a bus bar in which the resistivity likewise varies along the length. The resistivity can also be varied by other compositional adjustments such as the local inclusion of resistive materials in the bus bar or the variation of the composition of a conductive component to adjust its resistivity. Slight variations in composition can change the resistivity of certain conductive materials such as conductive polymers. In certain embodiments, the electrical conductivity of the bus bar material is constant, but the thickness and/or width of the bus bar varies along its length.

The value of the voltage that can be applied at any position on the bus bar is a function of the location where the bus bar connects to an external power source and the resistance profile of the bus bar. A bus bar may be connected to the source of electrical power at locations where the bus bar has least resistance, although this is not required. The value of the voltage will be greatest at the locations where the power source connection attaches to the bus bars. The decrease in voltage away from the connection is determined by the distance from the connection and the resistance profile of the bus bars along the path from the connection to the point where voltage is measured. Typically, the value of voltage in a bus bar will be greatest at the location where an electrical connection to the power source attaches and least at the distal point of the bus bar. In various embodiments, a bus bar will have lower electrical resistance at an end proximal to the connection to the electrical source and a higher resistance at a distal end (i.e. the resistance is higher at the distal end than at the proximal end).

Each of the lengthwise variable bus bars may have linearly, stepped, or otherwise varying geometry and/or material composition along its length. For example, a bus bar with lengthwise-varying geometry may have its width, height, and/or other cross-sectional dimension linearly tapering from the proximal end to the distal end. As another example, a bus bar may be comprised of multiple segments with stepwise decreasing widths or other dimensions from the proximal end to the distal end. In yet another example, a bus bar may have a material composition that varies lengthwise to increase electrical resistivity between proximal and distal ends.

FIGS. 4D and 4E depict EC lites, 425 and 435 respectively, each having a monolithic EC device on a transparent substrate and a pair of bus bars. The width of each of the bus bars varies along its length. This geometric lengthwise variation in the bus bars may produce a tint gradient zone (gradient in lengthwise direction) on the monolithic EC device when energized.

FIG. 4D depicts an EC lite, 425, including bus bars 430. Each of the bus bars 430 has a varying width along its length that linearly tapers lengthwise. In certain embodiments, the variation in width between the two ends may be between about 10% and about 100% from the average width over the length of the bus bar. In one embodiment, the variation in width may be between about 10% and about 80% from the average width over the length of the bus bar. In another embodiment, the variation in width may be between about 25% and about 75% from the average width over the length of the bus bar. In this example, not drawn to scale, the bus bars 430 are widest at the top of EC lite 425 and linearly taper lengthwise to their thinnest width near the bottom of lite 425. Because of the varying width, bus bars 430, when energized, establish a voltage gradient. For example, when energized, bus bars 430 have their highest effective voltage at the top, and their lowest voltage at their bottom portion; a voltage gradient is established along the bus bars. As depicted in the right portion of FIG. 4D, a corresponding tinting gradient is established by virtue of the voltage gradient. Thus a tint gradient zone is established. Bus bars of varying width can be used in one or more zones of an EC lite having two or more zones as described herein. In this illustrated example, a single tint gradient zone is established across an EC lite. Although a linearly tapered width is illustrated in FIG. 4D, a non-linearly tapered width can be used in other cases.

In certain embodiments, the tapering of the bus bars need not be a smooth taper. For example, a bus bar may have a stepped down width along its length (i.e. stepwise width variation along its length). FIG. 4E depicts an EC lite, 435, having a monolithic EC device and bus bars that have stepped widths along their lengths. Each bus bar has three segments with stepped down widths along its length. Each bus bar has a first width that spans a first portion, 440, of the length of the bus bar. Adjacent to the first portion, is a second portion, 445, of the length of each bus bar. The second portion has a second width shorter than the first width. Finally, adjacent to the second portion and having a third width, is a third portion, 450 of each bus bar. The net tinting gradient effect may be the same as or similar to the smooth linearly taper bus bars described in relation to FIG. 4D. One of ordinary skill in the art would appreciate that varying the width of the bus bars can be done in other patterns, such as thicker in the middle than at the ends, etc. without escaping the scope of embodiments described herein, that is for an EC lite having bus bars of varying widths configured to create one or more tint gradient zones on a monolithic EC device.

In one embodiment, an IGU includes two EC lites, each EC lite having a tint gradient zone as described in relation to FIGS. 4D and 4E. In one embodiment, the tint gradient zone of each EC lite is configured in opposition to each other, that is, one EC lite has a tinting front that starts at the opposite side (e.g., edge) of where the tinting front of the other EC lite starts. In this embodiment, a unique curtaining effect is established where the tinting fronts approach each other from opposite sides and cross paths in the middle of the IGU. In one case, when transition is complete in both EC lites, the IGU may have a “privacy glass” tint level, of e.g. <1% T. In another embodiment, each EC lite may be tinted independently to provide a “top down” tint gradient or “bottom up” tint gradient. In one embodiment, the tint gradient zones of the EC lites are registered together i.e. aligned so that the tinting fronts of the EC lites start on the same side of the IGU and end at the other opposing side. In this latter embodiment, tinting of the IGU may be done for different tint levels with one lite, e.g., to provide a top down tint gradient of one intensity (absorption gradient e.g.) for one tint level, and another (darker) tint level of tinting gradient when both lites are tinted. Either of the two aforementioned IGU embodiments may have their individual EC lites tinted together or alternatively tinted asynchronously for yet another shading effect that is not possible with conventional monolithic EC devices.

In one embodiment, a bus bar may include an inner portion of electrically conductive material with a cross-sectional dimension (e.g., width) that varies lengthwise, and an outer portion of electrically resistive material. The outer portion may have geometry which is designed to couple and form with the inner portion a uniform cross-section along the length of the bus bar.

In certain embodiments, such as some embodiments described above, an electrochromic window lite includes a monolithic EC device on a transparent substrate, wherein the EC lite includes at least one pair of bus bars configured to produce a tint gradient zone on the monolithic EC device when energized. In some embodiments, tinting gradients are established using bus bars, where each bus bar has at least two portions that are highly conductive. The at least two portions are separated by a portion that is more resistive than the highly conductive at least two portions, while still being electrically conductive. The more resistive portion is configured adjacent to or overlapping the at least two highly conductive portions. In this embodiment, the at least two highly conductive portions are separated, they do not touch, but rather each only touches, and is in electrical communication with the more resistive portion in between them. An electrical power source is configured to power only one portion of the at least two highly conductive portions of each of the at least one pair of bus bars. Each of the only one portion of the at least two highly conductive portions is proximate the same side of the monolithic EC device as the other of the only one portion. One of these embodiments is described in more detail in relation to FIG. 4F.

Tint gradient zones can also be created using bus bars having varying material composition along their lengths. For example, FIG. 4F depicts an EC lite, 455, having two bus bars, each configured along opposing edges (e.g., vertically, horizontally, etc.) and parallel to each other on lite 455. In this example, each bus bar has highly electrically conductive portions, 460 a, 460 b, and 460 c (collectively, 460), and less electrically conductive portions, 465 a and 465 b (collectively, 465). In the illustrated example, less electrically conductive portions, 465 a is between highly electrically conductive portions 460 a and 460 b, and less electrically conductive portions, 465 b is between highly electrically conductive portions 460 b and 460 c. The less electrically conductive portions, 465 a and 465 b, may be portions of a monolithic bus bar where the conductivity has been reduced by, e.g. changing the morphology of the bus bar material and/or perforating the material, etc. As an example, highly electrically conductive portions 460 a, 460 b, and 460 c may be conventional silver based conductive bus bar ink, while portions 465 a and 465 b may be a less conductive ink. In this illustrated example, the bus bars may be connected to an electrical source at the top portion, 460 a, of each bus bar. A voltage gradient may be established along the length of the bus bars by virtue of the resistive portions 465 a and 465 b. That is, the top highly conductive portions 460 a may have the highest voltage, and the middle highly conductive portions 460 b may have a somewhat lower voltage because the more resistive portions 465 a lie between them preventing some of the electrical current from flowing to the middle portions 460 b from portions 460 a. Likewise the bottom-most highly conductive portions 460 c may have the lowest voltage because the more resistive portions 465 b lie between them and the middle highly conductive portions 460 b preventing some of the electrical current from flowing from middle portion 460 b to lower portion 460 c. The net effect may be a tint gradient zone, for example, the one depicted in FIG. 4F. Highly electrically conductive portions 460 may be of the same or different conductive material, and likewise, less electrically conductive portions 465 may be comprised of the same or different conductive material. The key is that portions 465 are less electrically conductive than their adjacent neighbors 460. Using this technology, a wide variety of voltage and/or resistance patterns may be established in order to create corresponding tint gradient zones in an EC lite. In addition, a combination of bus bars of lengthwise varying width and those bus bars configured as described in relation to FIG. 4F may be used. For example, each as partners in a bus bar pair and/or in individual tint gradient zones on an EC lite.

In certain embodiments, an EC lite may be configured to have a combination of tint gradient zones and tint zones that do not have tint gradient capability (non-gradient tint zones). One embodiment is a monolithic EC device having two or more tinting zones, where at least one tinting zone is a tint gradient zone and at least one tinting zone is a non-gradient tint zone. One embodiment is a monolithic EC device having two or more tint gradient zones, with or without also having a non-gradient tint zone.

In one embodiment, the bus bars described in relation to FIG. 4F are configured such that each highly electrically conductive portion, 460 a, 460 b, and 460 c, has its own electrical connection to a power source. Analogous to the separate bus bar pairs described in relation to FIG. 4A (or FIG. 3A or 3D), the bus bars described in relation to FIG. 4F, when configured with each highly electrically conductive portion 460 having its own power source, may be used to create tint gradient zones with tinting patterns similar to those described in relation to FIGS. 4B and 4C.

In certain embodiments that use powering mechanisms alone to create tinting zones, the tinting front may not be a clean line, but rather have a diffuse appearance along the tinting front due to the charge bleeding off into the EC device's adjacent zone which is not powered at the time. In certain embodiments, resistive zones may be used to aid in maintaining more well-defined tinting fronts. Resistive zones are described in more detail below.

Resistive Zones with or without Configuring Powering Mechanism of EC Devices

In certain embodiments, resistive zones are configured in the monolithic EC device. These resistive zones may allow for more uniform tinting fronts, e.g., when used in combination with bus bar powering mechanisms described herein. Referring to FIG. 5A, an EC lite, 500, much like EC lite 200 of FIG. 2A, is configured with two pairs of bus bars for creating two tinting zones, in this example (as depicted) a top and a bottom zone. EC lite 500 may be incorporated into an IGU, 510, with a spacer 110 and a mate lite 115 as depicted. A major difference between lite 200 of FIG. 2A and lite 500 of FIG. 5A is that lite 500 does not have a laser scribe 225 across the lite to bifurcate the EC device into two devices. Lite 500 has a single EC device over the viewable area of the lite. However, the EC device on lite 500 includes a resistive zone, 505, that spans the width of the EC device. The heavy dotted line in FIG. 5A indicates the approximate position of resistive zone 505. As depicted in the IGU construct 510, resistive zone 505, like laser scribe 225, may not be visible to the naked eye when the EC lite's zones are not tinted. However, unlike laser scribe 225, when adjacent tinting zones of EC lite are tinted, resistive zone 505 may not be visually discernible to the naked eye. This is illustrated schematically in the right portion of FIG. 5B. The reason resistive zone 505 tints is because it is not a physical bifurcation of the EC device into two devices, but rather a physical modification of the single EC device and/or its associated transparent conductors within a resistive zone. The resistive zone is an area of the EC device where the activity of the device, specifically the electrical resistivity and/or resistance to ion movement is greater than for the remainder of the EC device. Thus one or both of the transparent conductors may be modified to have increased electrical resistivity in the resistive zone, and/or the EC device stack may be modified so that ion movement is slower in the resistive zone relative to the EC device stack in the adjacent tinting zones. The EC device still functions, tints and bleaches, in this resistive zone, but at a slower rate and/or with less intensity of tint than the remaining portions of the EC device. For example, the resistive zone may tint as fully as the remainder of EC device in the adjacent tinting zones, but the resistive zone tints more slowly than the adjacent tinting zones. In another example, the resistive zone may tint less fully than the adjacent tinting zones, and at a slower rate.

FIG. 5C is a perspective and a cross section, X-X, of EC lite 500 as described with respect to FIGS. 5A and 5B. The cross section, X-X, spans the upper and lower tinting zones (tinting zones 1 and 2, respectively) of EC lite 500 as well as resistive zone 505 (only the bus bars on the top TCO are depicted in cross section X-X, they are orthogonal to resistive zone 505 in this example). Cross section X-X (lower portion of FIG. 5C) is not to scale, but rather a schematic representation of the structure of EC lite 500. On the glass substrate is an EC device including a first transparent conducting oxide layer, TCO 1, a second transparent conductive oxide layer, TCO 2, and sandwiched in between the TCOs is an EC stack which contains one or more electrochromic materials, e.g., the transitions of which are driven by intercalation/de-intercalation of ions, such as lithium ions. Resistive zone 505 is an area in the EC device where one or more layers of the EC device have their function impaired, either partially or completely, but device function is not cut off across the zone. For example, one or both of the TCOs has a higher resistance to electrical flow in resistive zone 505 than in the tinting zones. Thus, e.g., if tinting zone 1 is activated, electrons flow across the TCOs at a given rate, but that flow is restricted along resistive zone 505. This allows the electrons to be sufficiently retained in tinting zone 1 and thus leak more slowly across resistive zone 505 than otherwise would be the case if TCO function had not been impaired there. Resistive zone 505 could be thought of as a “dam” for electrical flow, impairing rate of electrical flow across it, the flow can be partially or fully impaired in one or both TCOs, for example. Due to the restricted or slowed rate of electrical flow across resistive zone 505, ion intercalation in the EC stack between the TCOs at resistive zone 505 is also impaired. Because the EC device is not physically cut into two devices, this is unlike conventional devices having zones created by physical bifurcation of a single device. Resistive zone 505 may also have physical impairment of ion flow in one or more of the EC material layers as well. In one example, both the top and bottom TCO's electrical conductivity is impaired, either partially or fully, in resistive zone 505, but the function of the EC device stack layers is substantially unchanged. Thus, when one tinting zone is tinted and the adjacent zone is not-tinted, the device will tint under resistive zone 505. When adjacent tinting zones are both tinted, there is no bright line discernible to the end user, because the device tints under resistive zone 505.

Resistive zone 505 may be fabricated, for example, by exposure of the area at the resistive zone 505 to irradiation, e.g. laser or heat source, in order to modify but not destroy the function at resistive zone 505. For example, one or both of the TCO layers may be heated sufficiently to change the morphology while retaining the function, albeit impaired relative to the remainder of the TCO layers in the tinting zones. In certain embodiments, it is advantageous to impair the function of only one TCO in a resistive zone. Resistive zones may also be created by impairing the function of one or more layers of the EC device (or one or both TCOs) by chemical doping. For example, in one embodiment the lower TCO is treated along a line (at resistive zone 505, e.g.) with heat and oxygen to create a more resistive TCO at the resistive zone. In another embodiment, one or both TCOs are fabricated thinner along the resistive zone than the rest of the TCOs, e.g. TCO material may be removed, but not cut through, along the resistive zone.

In certain embodiments, the resistive zones may be narrow, e.g. between about 1 μm and 1000 μm wide, or may be wider, e.g. between about 1 mm and about 10 mm wide. Because the EC materials in resistive zones tint and do not necessarily leave a bright line contrast effect typical of conventional laser isolation scribes, there is less concern as to the width of the described resistive zones. Thus, in other embodiments, a resistive zone may be, for example, wider than 1 mm, wider than 10 mm, wider than 15 mm, etc.

In the embodiment described in relation to FIGS. 5A, 5B, and 5C, each of the tinting zones has its own pair of bus bars. Thus tinting zones can be colored independently by virtue of operation or the respective bus bar pairs at each tinting zone. In other embodiments, multiple tinting zones may be configured between a single set of bus bars (e.g., two or more bus bars located on opposing edges).

FIG. 5D depicts a perspective (top portion) and a cross section Y-Y (bottom portion) of an EC lite, 510, having two tinting zones of variable tinting level by virtue of a resistive zone, 515. In this illustrated example, a single set of three bus bars, 525(a), 525(b), and 520, is used with two tinting zones. Cross section, Y-Y, of EC lite 510 spans left and right tinting zones (tinting zones 1 and 2, respectively) of lite 510 as well as resistive zone 515. Resistive zone 515 runs parallel to and between (approximately in the middle of EC lite 510) bus bars 520 and 525(a) and bus bar 525(b) (from top to bottom as depicted in the perspective at the top of FIG. 5D). Cross section Y-Y (lower portion of FIG. 5D) is not to scale, but rather is a schematic representation of the structure of EC lite 510. On the glass substrate is an EC device including a first transparent conducting oxide layer, TCO 1, a second transparent conductive oxide layer, TCO 2, and sandwiched in between TCO 1 and TCO 2 is an EC stack which contains one or more electrochromic materials, e.g., the transitions of which are driven by intercalation/de-intercalation of ions, such as lithium ions. In this example, resistive zone 515 is an area of TCO 2, where the TCO function is impaired but not eliminated. For example, TCO 2 may have its function impaired along a line. FIG. 5E includes two graphs showing plots of the local voltage V_(TCL), in TCO 1 and TCO 2 of the EC lite, 510, of FIG. 5D that drives transition. At the left, a graph shows a curve 526 of the local values of V_(TCL), in the TCO 1. At the right, a graph shows a curve 528 of the local values of V_(TCL) in the TCO 2. In this example, when the EC device is energized, the bottom TCO 1 has a local voltage potential V_(TCL) across its span similar to that of a typical transparent conductor for an EC device. According to curve 526 of V_(TCL), in TCO 1, the voltage increases slightly in the middle away from where bus bars 525(a) and 525(b) are disposed on TCO 1 where voltage is applied due to the sheet resistance and current passing through TCO 1. The increase will be near bus bar 525(a) and bus bar 520 because of the higher current in this area due to higher voltage potential between bus bar 525(a) and bus bar 520. But TCO 2, by virtue of resistive zone 515, has a higher V_(TCL), in tinting zone 1 than in tinting zone 2. According to curve 528 V_(TCL), in TCO 2, the slight voltage drops between the left hand side where bus bar 520 is disposed on TCO 2 and the resistive zone due to sheet resistance and current passing through TCO 2. At the resistive zone 515, the voltage sharply drops. The voltage slightly drops between the resistive zone 515 and the right hand side due to sheet resistance and current passing through TCO 2. The value of V_(eff) at any location between the bus bars is the difference in values of curves 130 and 125 at that position on the x-axis corresponding to the location of interest. The result is that tinting zone 1 has a higher V_(eff) than tinting zone 2 and thus tinting zone 1 colors more darkly than tinting zone 2. This is represented in FIG. 5F. Of course, the two tinting zones can be configured as upper and lower portions when installed in a building, and they need not be side by side as depicted.

FIG. 5G depicts an EC lite, 530, configured with a resistive zone created by inhibiting the electrical conductivity of only one of the transparent conducting oxides. The EC lite is much like the one described in relation to FIG. 5E, but in this embodiment one of the TCOs is cut through along the resistive zone (cut 550), while the other TCO is left intact. The EC device stack is unchanged in the resistive zone, only the top TCO is cut. The EC lite 530 has two sets of bus bars, 535 and 540. Bus bar set 535 powers the lower TCO 1, while bus bar set 540 powers the top TCO 2. The lower portion of FIG. 5G shows cross section Z-Z. The EC device will still at least partially color along the resistive zone by virtue of one of the TCOs being fully intact, monolithic, along with the EC stack. While there is a narrow region of the opposite TCO 2 missing, there is sufficient voltage potential established between the intact TCO 1 and the edge of the cut (opposing) TCO 2 along the resistive zone to allow coloration of the EC device in the resistive zone, albeit more slowly than if both TCOs were intact along the resistive zone. The resistive zone may color more lightly when only one of the tinting zones is powered, while with both tinting zones powered, the resistive zone may fully tint or approximate full tinting. Each portion of TCO 2 can be powered independently of TCO 1. In this way, separate zones, tinting zone 1 and tinting zone 2, may, e.g., be tinted more effectively. Since there is a cut through the TCO 2, if only one zone is powered, a tinting level of V_(TCL) is only established in that tinting zone. The cut in TCO 2 aids in establishing and maintaining a uniform tinting front. In this example, since the TCOs are a type of moisture barrier, EC lite 530 may be incorporated into an IGU where the EC device is hermetically sealed within the volume of the IGU, and/or a top coat may be used to hermetically seal the device, with our without lamination to a substrate. A top coat would fill the open trench cut through TCO 2.

In certain embodiments, it may be more desirable to cut the bottom TCO 1 rather than the top TCO 2. FIG. 5H shows EC lite, 530 a, where the cut, 550 a, is made only through the bottom TCO 1. In this example, the top TCO 2 may maintain its hermeticity by virtue of an intact top transparent conductor layer. The EC material may fill in the trench made by cut 550 a, and thus tint along with the trench in TCO 1 that it fills, providing an area of inhibited coloration rate such as a resistive zone.

In certain embodiments, it may more desirable to cut the top TCO 2 rather than the bottom TCO 1. FIG. 5G shows EC lite, 530, where the cut, 550, is made only through the top TCO 2. An advantage of this embodiment may be that the cut can be made after the EC device is fabricated, for example, by laser processing performed after sputter coating.

The busbars 535 and 540 depicted in FIGS. 5G and 5H need not be parallel, e.g. the bus bars powering each TCO can be orthogonal to each other. Also, the single monolithic TCO need not have two bus bars, but it is desirable so as to have more control over tinting of the individual tinting zones. Bleaching function would work the same way but in reverse polarity to bleach the tinting zones. In the embodiments described in relation to FIGS. 5D-5H, the bus bars are configured parallel to the resistive zone; in FIGS. 5I and 5J, like in FIG. 5C, e.g., the bus bars are configured orthogonally to the resistive zone.

In certain embodiments, there are no bus bars in the viewable area of the EC device, that is, in the area within the spacer of the IGU. Certain conventional EC technologies rely on bus bars running through the viewable area because of slow switching kinetics that would otherwise occur and/or due to ion conductor layer leakage currents that do not allow the EC device to switch across the entire viewable area of larger IGUs (e.g. about a meter wide or more where bus bars would otherwise be configured outside the viewable area at the edges of this width) without such bus bars in the viewable area to provide the extra voltage needed to compensate for the leakage current. Certain embodiments described herein, e.g. where cuts are made through one of the TCOs but not the EC device stack itself, do not require bus bars in the viewable area because they include EC devices with very low leakage current. Examples of such devices are described in U.S. patent Ser. No. 12/814,279, filed Jun. 11, 2010, which is herein incorporated by reference in its entirety. For example, the embodiments described where the resistive zone includes a cut through one of the TCOs include examples where there are no bus bars in the viewable area of the EC device.

FIG. 5I depicts an EC lite, 555, configured with a resistive zone, 570, created by inhibiting the electrical conductivity across one of the transparent conducting oxides, in this example a cut is made through the TCO nearer the substrate. The EC lite is much like the one described in relation to FIG. 5C, but in this embodiment one of the TCOs is cut through along the resistive zone (cut 570), while the other TCO is left intact. The EC device stack is unchanged in the resistive zone area, only the bottom TCO is cut. The EC lite 555 has two sets of bus bars, 560 and 565. Bus bar set 560 powers both the upper and the lower TCOs in tint zone 1 (TCO 1 and TCO 2), while bus bar set 565 powers tint zone 2. The lower portion of FIG. 5I shows cross section V-V (only the bus bars on TCO 2 are depicted). The EC device will still at least partially color along the resistive zone by virtue of one of the TCOs being fully intact, monolithic, along with the EC stack. While there is a narrow region of the opposite TCO 1 missing, there is sufficient voltage potential established between the intact TCO 2 and the edge of the cut (opposing) TCO 1 along the resistive zone to allow coloration of the EC device in the resistive zone, albeit more slowly than if both TCOs were intact along the resistive zone. The resistive zone may color more lightly when only one of the tinting zones is powered, while with both tinting zones powered, the resistive zone may fully tint or approximate full tint. Each portion of TCO 1 can be powered independently of TCO 2. In this way, separate zones, tinting zone 1 and tinting zone 2, may, e.g., be tinted more effectively. Since there is a cut through the TCO 1, if only one zone is powered, a tinting level V_(TCL) is only established in that tinting zone. The cut in TCO 1 aids in establishing and maintaining a uniform tinting front. In this example, since the TCOs are a type of moisture barrier, EC lite 555 may be incorporated into an IGU where the EC device is hermetically sealed within the volume of the IGU, and a top coat may not be necessary because TCO 2 remains intact, although in one embodiment a top coat is applied to TCO 2. Because the bus bars in EC lite 555 are orthogonal to the resistive zone 570, the tinting front is also orthogonal to the bus bars.

FIG. 5J depicts an EC lite, 555 a, configured with a resistive zone, 570 a, created by inhibiting the electrical conductivity across one of the transparent conducting oxides, in this example a cut is made through the TCO distal the substrate. The EC lite is much like the one described in relation to FIG. 5I, but in this embodiment TCO 2 is cut through while TCO 1 is left intact. The EC device stack is unchanged in the resistive zone area, only the top TCO is cut. The EC lite 555 a has two sets of bus bars, 560 and 565. Bus bar set 560 powers both the upper and the lower TCOs in tint zone 1 (TCO 1 and TCO 2), while bus bar set 565 powers tint zone 2. The lower portion of FIG. 5J shows cross section T-T (only the bus bars on TCO 2 are depicted). The EC device will still at least partially color along the resistive zone by virtue of one of the TCOs being fully intact, monolithic, along with the EC stack. While there is a narrow region of the opposite TCO 2 missing, there is sufficient voltage potential established between the intact TCO 1 and the edge of the cut (opposing) TCO 2 along the resistive zone to allow coloration of the EC device in the resistive zone, albeit more slowly than if both TCOs were intact along the resistive zone. The resistive zone may color more lightly when only one of the tinting zones is powered, while with both tinting zones powered, the resistive zone may fully tint or approximate full tinting. Each portion of TCO 2 can be powered independently of TCO 1. In this way, separate zones, tinting zone 1 and tinting zone 2, may, e.g., be tinted more effectively. Since there is a cut through the TCO 2, if only one zone is powered, a tinting level of V_(TCL), is only established in that tinting zone. The cut in TCO 2 aids in establishing and maintaining a uniform tinting front. In this example, since the TCOs are a type of moisture barrier, EC lite 555 a may be incorporated into an IGU where the EC device is hermetically sealed within the volume of the IGU, and a top coat may be necessary because TCO 2 is cut through, in one embodiment a top coat is applied to TCO 2. Because the bus bars in EC lite 555 a are orthogonal to the resistive zone 570 a, the tinting front is also orthogonal to the bus bars.

When two bus bars ends of opposite polarity are located proximate each other on an intact TCO, hot spots can result. Hot spots are described in U.S. patent application Ser. No. 13/452,032, filed Apr. 20, 2012 which is incorporated by reference herein in its entirety. When using TCOs that are cut through, e.g. as depicted in FIG. 5J, hot spots may be avoided because the proximate bus bars of a TCO layer cannot electrically communicate with each other through the TCO. However, to avoid stress on the underlying EC device in the area along the resistive zone formed by cutting through TCO, the ends of the bus bars may be configured so they are not directly over (aligned with) the cut made for the resistive zone.

One embodiment is an EC lite as described herein, where a resistive zone is formed by partially cutting through one or both of the TCOs. For example, in one embodiment, e.g. analogous the embodiment described in relation to FIG. 5J, the top TCO is only cut part way through, rather than cut through. In this way a resistive zone is established and the hermiticity of the EC device, imparted by the top TCO is left at least partially intact. FIG. 5K depicts another example.

FIG. 5K depicts an EC lite, 575, configured with two resistive zones, 580 a and 580 b, created by inhibiting the electrical conductivity across one of the transparent conducting oxides. In this example, partial cuts are made through the TCO distal the substrate (TCO 2). The EC lite is much like the one described in relation to FIG. 5J, but in this embodiment TCO 2 is not cut through, but only some TCO material is removed to form resistive zones 580 a and 580 b. For example, laser ablation is used to remove material only down to a fraction of the depth of the ITO. In one embodiment, between about 10% and about 90% of the TCO material is removed along the zone, in another embodiment between about 25% and about 75% of the TCO material is removed, in yet another embodiment between about 40% and about 60% of the material is removed. By removing only part of the TCO material, a resistive zone is fabricated while not exposing the EC stack to the ambient. Lite 575 has three tint zones, by virtue of having two resistive zones. The EC lite 575 has three sets of bus bars, 560, 565 and 566. Bus bar set 560 powers both the upper and the lower TCOs in tint zone 1 (TCO 1 and TCO 2), bus bar set 565 powers tint zone 2, and bus bar set 566 powers tint zone 3. Each tint zone can be independently controlled via powering the bottom TCO, and independently charging the TCO 2 bus bars, depending upon which zone tinting is desired. Because the resistive zones have a higher sheet resistance relative to the bulk TCO, charge loss over this barrier is slow and allows the powered zone to fully tint while the tinting front approximates the position of the resistive zone.

The lower portion of FIG. 5K shows cross section S-S (only the bus bars on TCO 2 are depicted). The EC device will still at least partially color along the resistive zone by virtue of TCO 2 being fully intact, monolithic, along with the EC stack. The resistive zone may color more lightly when only one of the tinting zones is powered, or not at all, depending on its width and the thickness of the TCO in the resistive zone. With adjacent tinting zones powered, the resistive zone may fully tint or approximate full tinting. In this example, since the TCOs are a type of moisture barrier, EC lite 575 may be incorporated into an IGU where the EC device is hermetically sealed within the volume of the IGU, and a top coat may be necessary because TCO 2 is at least partially cut through, in one embodiment a top coat is applied to TCO 2. Because the bus bars in EC lite 575 are orthogonal to the resistive zones 580 a and 580 b, the tinting front is also orthogonal to the bus bars and approximates the line defined by the resistive zones.

Note, in FIG. 5K, the bus bars ends are substantially coextant with the resistive zones. In one embodiment, bus bar material is applied and then the resistive zones are formed by cutting through the bus bar material and at least some of the top TCO. In certain embodiments the top TCO is cut through, while not cutting the EC device stack through (a portion of the EC stack may be cut, but sometimes not through the IC material so as not to form electrical shorts along the resistive zone). By applying, e.g., only two lines of bus bar material (e.g. silver based ink) and firing the bus bars, the resistive zones and individual bus bar pairs can be fabricated in the same process by cutting through the bus bar material and into or through the top TCO simultaneously. This saves process steps. The bus bar on the bottom TCO 1 is cut through without cutting through the bottom TCO. In one embodiment the bus bars on the top TCO are formed by cutting through along with the top TCO, either fully or partially cut, while the bottom bus bars are applied separately to each tinting zone. In certain embodiments, each tinting zone's bus bars are applied individually to each tinting zone. The latter may be done to avoid the aforementioned hot spots, e.g. when cutting through the bus bar and TCO in the same process, the ends of the newly formed bus bars are necessarily aligned with the cut in the TCO, since they were from the same cutting process.

Certain embodiments concern methods of fabricating apparatus and devices described herein. One embodiment is a method of forming an EC lite having two or more tinting zones, the method including a) forming a EC device (e.g., a monolithic EC device), b) applying a single bus bar to the top TCO of the monolithic EC device, and c) cutting through the bus bar and at least part way through the top TCO thereby fabricating said two or more tinting zones each having separate bus bars on the top TCO by virtue of c.

Resistive zones need not be linear as depicted, but rather may be of any shape. For example, for desired effects, one might choose a resistive zone that is zigzagged, curved or irregularly shaped along adjacent tinting zones.

In certain embodiments, resistive zones are used to define a perimeter, closed or open, of a region of an EC window. For example, these resistive zones can be used to highlight particular symbols or shapes in the viewable region of the EC window. One embodiment with such a resistive zone is illustrated in FIGS. 6A and 6B. For example, an end user may wish to have an area of the EC window that does not tint, or that becomes tinted more slowly, than the remainder of the tintable EC window.

FIG. 6A depicts an EC lite, 600, which includes a single pair of bus bars, 105, as well as a resistive zone, 605. In this example, the resistive zone is in the shape of a closed rectangle (as indicated by the dotted line). Resistive zone 605 may not be visually discernible to the naked eye. In one embodiment, resistive zone 605 is configured such that the portions of the TCOs of the EC device in the resistive zone (as indicated by the dotted line) have a higher electrical resistance than the portions of the TCOs in the remainder of the EC device on either side of the resistive zone (in this example both outside and inside the rectangular perimeter zone), but the resistive zone still passes charge. In this embodiment, when the EC device is tinted, the area around the resistive zone 605 tints first, the tinting front slowing when it reaches the rectangular closed resistive zone 605. This momentarily, e.g. for a period of minutes, gives the effect of a small untinted view port in a larger tinted window. As the charge bleeds beyond the resistive zone and into the untinted rectangular region within the zone, this gives the effect of the small untinted view port closing as it tints. In another embodiment, resistive zone 605 is configured such that the portions of the TCOs of the EC device in the resistive zone (as indicated by the dotted line) have a very high resistance to electrical charge as compared to the portions of the TCOs in the remainder of the EC device on either side of the resistive zone (in this example both outside and inside the rectangular perimeter zone), that is, the resistive zone effectively blocks electrical charge. In this embodiment, when the area outside the zone is tinted, the area inside the zone may never tint because the charge may not be able to pass the resistive barrier 605. This gives the effect of a small untinted view port in a larger tinted window, so long as the EC device is tinted. In another embodiment, resistive zone 605 is configured such that the portions of the TCOs of the EC device in the resistive zone (as indicated by the dotted line) and in the region within the resistive zone have a very high resistance to electrical charge as compared to the portions of the TCOs in the remainder of the EC device on the outside of the resistive zone.

FIG. 6B shows a similar EC lite, 610, having a resistive zone, 615, which is “open” by virtue of a gap, 620, in the perimeter. In this example, the resistive zone 615 is configured to block electrical charge. When the EC device is tinted, the area around the resistive zone 615 tints first, the tinting front slowing when it reaches the rectangular closed resistive zone 615, except at the open portion 620, where the tinting front gives the effect of “pouring in” or “filling in” (as indicated by the two dotted arrows) the rectangular region within resistive zone 615. Eventually, when the area inside resistive zone 615 is tinted, resistive zone 615 may no longer be discernible to the naked eye, as the EC device colors under the zone, as described above. Configuring resistive zones in such a way can be used to achieve permanent or transient tinting effects on EC windows, e.g., to display a logo or words in a transient manner for presentation during marketing purposes, or to achieve tinted and non-tinting zones on an EC lite. EC lites so configured can be incorporated into IGUs as describe and/or laminated with mate lites.

One of ordinary skill in the art, armed with this disclosure, would appreciate that tint gradient zones can be used with resistive zones and this combination is within the scope of the embodiments described herein.

Although the foregoing embodiments have been described in some detail to facilitate understanding, the described embodiments are to be considered illustrative and not limiting. It will be apparent to one of ordinary skill in the art that certain changes and modifications can be practiced within the scope of the above description and the appended claims. 

We claim:
 1. An electrochromic window comprising: an EC device disposed on a transparent substrate, the EC device comprising a first transparent conducting oxide (TCO) and a second TCO; and a pair of bus bars coupled to the first and second TCOs and disposed continuously along opposing edges of the electrochromic device, wherein each bus bar is configured to generate and maintain a voltage drop along the bus bar's length when voltage is applied, so that the electrochromic window maintains a tint gradient along its length.
 2. The electrochromic window of claim 1, wherein the voltage drop is achieved by varying thickness or width along the length of each of the pair of bus bars.
 3. The electrochromic window of claim 1, wherein the voltage drop is achieved by varying composition along the length of each of the pair of bus bars.
 4. The electrochromic window of claim 1, wherein the voltage drop is achieved by varying resistivity along the length of each of the pair of bus bars.
 5. The electrochromic window of claim 4, wherein each bus bar of the pair of bus bars comprises two portions of an electrically conductive material, and an electrically resistive material establishing electrical communication between the two portions of the electrically conductive material, the electrically resistive material, although electrically conductive, having less electrical conductivity than the electrically conductive material.
 6. The electrochromic window of claim 5, wherein the electrically conductive material is a silver based ink.
 7. The electrochromic window of claim 5, wherein the electrically resistive material is a silver based ink.
 8. The electrochromic window of claim 1, wherein the voltage drop is achieved by varying cross-sectional area along the length of each of the pair of bus bars.
 9. The electrochromic window of claim 1, wherein the voltage drop is achieved by varying morphology along the length of each of the pair of bus bars.
 10. The electrochromic window of claim 1, wherein voltage is applied at one or both ends of each of the pair of bus bars.
 11. The electrochromic window of claim 1, wherein voltage is applied at more than one point along at least one of the pair of bus bars.
 12. The electrochromic window of claim 11, wherein each bus bar of the pair of bus bars comprises a pair of power leads.
 13. The electrochromic window of claim 12, wherein each bus bar of the pair of bus bars is configured to be powered by a first voltage at one power lead and by a second voltage at the other power lead.
 14. The electrochromic window of claim 1, wherein each bus bar of the pair of bus bars comprises a material having regions of higher and lower electrical conductivity, wherein the regions of lower electrical conductivity are areas where the material is perforated. 